Would You Rather Be Skinny On The Outside Or The Inside?

I know a woman who eats M&Ms like she's paid to—dedicatedly. She doesn't consume enough calories to be fat, so she doesn't need exercise to maintain her weight. She just doesn't think about food—she'll eat fries when they're around, have a milkshake for lunch, skip dinner on occasion because she can't be bothered, not because she's trying to lose weight. And I don't think she's ever seen the inside of a gym—but she's thin.

Do you know people like this? Are you people like this? :- )

So here's my question: Would you rather be a size 4 and pretty unhealthy—not to mention, nutrient deficient—unable to walk up a flight of stairs without getting winded? Or would you rather be a size 12 but "skinny on the inside"—fit with a healthy heart and strong body that would have you running circles (and miles) around your size 4 friend?

If you had to make a choice between being bigger and healthier or skinny but not healthy at all, which would you choose? Be honest!